The invention relates to a golf club head. More particularly, the invention relates to a golf club head with a face having different radii of curvature on interior and exterior surfaces.
The design of club heads has long been studied. Among the more prominent considerations in club head design are loft, lie, face angle, horizontal face bulge, vertical face roll, face progression, sole curvature, center of gravity location, and overall head weight. Although all of these aspects may be considered in golf club engineering, several are often accorded more weight in the design process due to their significant impact on club performance.
Golf club heads must be strong enough to withstand the impact forces that occur during collision between the head and the ball. The loading that occurs during this event can cause an acceleration to the golf ball that is four orders of magnitude greater than that of gravity. Thus, the club face and body should be designed to resist permanent deformation or catastrophic failure, such as by material yield or fracture. Thus, for example, it is not unusual for club heads of prior art hollow metal woods, produced from titanium, to have a generally uniform face thickness exceeding 0.15 inches. This thickness has been required to ensure structural integrity of the club head during impact.
Players generally seek a golf club and golf ball combination that delivers maximum distance and landing accuracy. The distance a ball travels after impact is dictated by the magnitude and direction of the ball""s translational velocity and the magnitude and direction of the ball""s rotational velocity or spin. Environmental conditions, including atmospheric pressure, humidity, temperature, and wind speed further influence ball flight. However, these environmental effects are beyond the control of the golf equipment manufacturer. Golf ball landing accuracy is driven by a number of factors as well. Overall, among the factors that can be controlled during club head design, the center of gravity and club face flexibility can have a significant influence on the performance of the club head.
The United States Golf Association (USGA), the governing body for the rules of golf in the United States, has specifications for the performance of golf balls. These performance specifications dictate the size and weight of a golf ball that conforms to the USGA. Furthermore, there are USGA rules which limit the golf ball velocity after a prescribed impact. To achieve greater golf ball distance, ball velocity after impact must be maximized while remaining within USGA guidelines. This may be accomplished by allowing more club face deformation during impact. A variety of techniques may be utilized to vary the allowable deformation of the club face. For example, uniform face thinning, thinned faces with ribbed stiffeners, and a varied thickness on the face profile are three possibilities. Any design must have sufficient structural integrity to withstand impact without permanent deformation of the club face.
For example, U.S. Pat. No. 5,954,596 to Noble et al. discloses a golf club head with a reinforced front wall. The front wall of the body varies in thickness in two planes including a first plane that is disposed substantially horizontally between the top and bottom walls of the body and a second plane that is disposed substantially vertically between the heel and toe ends of the head. The body front wall has a bulge of increased thickness formed on the inner surface to increase thickness.
U.S. Pat. No. 5,830,084 to Kosmatka discloses a contoured golf club face that includes a vertical stiffening region and a horizontal stiffening region. This creates four similar contoured quadrants of increasingly thinning material toward the center of each quadrant, with thickening regions at face/sole and face/crown intersection regions. The thicknesses of adjoining regions are gradually blended to provide a smooth contoured surface.
Despite the several aforementioned club head designs, there remains a need for a wood-type golf club with a face that provides improved hitting performance through the structural design of the face. More particularly, there remains a need for a wood-type golf club head with a multi-radius face having different interior and exterior radii.
The present invention is related to a metal wood golf club head adapted for attachment to a shaft. The club head includes a body having a crown region, a sole region, a toe region, a heel region, and a ball-striking face extending therebetween. The face has an exterior surface substantially disposed at a first vertical roll radius and an interior surface substantially disposed at a second vertical roll radius. The first vertical roll radius is less than the second vertical roll radius. In one embodiment, the first vertical roll radius is between about 12 inches and about 18 inches, and the second vertical roll radius is between about 15 inches and about 50 inches. The second vertical roll radius may be at least about 1.2 times greater than the first vertical roll radius. In another embodiment, a portion of the inner surface is substantially planar.
The interior surface of the face may include a central thickened region having a ring portion and a plurality of branch portions radiating thereabout. The branch portions may be generally triangular.
In some embodiments, the exterior surface is further substantially disposed at a first horizontal bulge radius and the interior surface is further substantially disposed at a second horizontal bulge radius, with the first horizontal bulge radius being less than the second horizontal bulge radius. The first horizontal bulge radius may be between about 8 inches and about 12 inches, while the second horizontal bulge radius may be between about 15 inches and about 50 inches. The second horizontal bulge radius may be at least about 1.2 times greater than the first horizontal bulge radius, and a portion of the inner surface may be substantially planar. The central thickened region may include a plurality of branch portions radiating about a central point.
The present invention also is related to a metal wood golf club head adapted for attachment to a shaft, including a shell defining a body and further including a face. The face has an exterior surface and an interior surface, with the exterior surface being substantially defined along a first radius and the interior surface being substantially defined along a second radius, such that the first radius is less than the second radius. In some embodiments, the first radius and the second radius are vertical roll radii. The first radius may be between about 12 inches and about 18 inches, and the second radius may be at least about 15 inches. In addition, a central thickened region may be provided on the interior surface, and may have a ring portion with a plurality of branch portions radiating thereabout.
The present invention further is related to a face adapted for attachment to a body of a golf club head, consisting essentially of an exterior surface having a first vertical roll radius, an interior surface having a second vertical roll radius, wherein the first vertical roll radius is substantially less than the second vertical roll radius. The interior surface also may include a perimetral rim, and the exterior surface also may include a plurality of grooves. The first vertical roll radius may be between about 12 inches and about 18 inches, while the second vertical roll radius may be between about 15 inches and about 50 inches. The second vertical roll radius may be at least about 1.2 times greater than the first vertical roll radius, and a portion of the inner surface may be substantially planar.